A full-wave rectifying circuit is typically used to obtain a DC voltage from a single-phase AC voltage input from a single-phase AC power supply. Output of the full-wave rectifying circuit, however, has power pulsations having a frequency twice the frequency of the single-phase AC voltage. To reduce the power pulsations, a power buffer circuit for buffering a power is required between an output of the full-wave rectifying circuit and a load. A capacitive element, for example, referred to as a smoothing capacitor is required for buffering of a power.
Irie, Yamashita, and Takemoto, “Ripple Compensation for a Single-Phase Rectifier by 2-Quadrant Chopper and Auxiliary Capacitor”, the Institute of Electrical Engineers of Japan Transactions D, Vol. 112, No. 7, pp. 623-629 (1992) discloses a technique for connecting a buffer capacitor to a smoothing capacitor via a current-reversible chopper to absorb a pulsating power. This technique reduces the electrostatic capacitance of the smoothing capacitor and further allows voltage ripples on a buffer side to significantly reduce the total electrostatic capacitance required for smoothing.
Ohnuma, Itoh, “Circuit Configuration and Control Strategy of single-to-three Phase Power Converter with Active Buffer and Charge Circuit”, the 2010 Annual Meeting of the Institute of Electrical Engineers of Japan, 4-057 (2010) discloses a technique for connecting a buffer capacitor to a DC link via a switching element while removing the smoothing capacitor of Irie, Yamashita, and Takemoto, “Ripple Compensation for a Single-Phase Rectifier by 2-Quadrant Chopper and Auxiliary Capacitor”, the Institute of Electrical Engineers of Japan Transactions D, Vol. 112, No. 7, pp. 623-629 (1992). A direct conversion circuit that generates a voltage source by using this technique, and generates a high-frequency link along with a power supply voltage is shown.
Ohnuma, Itoh, “Comparison between a Boost Chopper and an Active Buffer as a Single to Three Phase Converter”, the 2011 Annual Meeting of the Institute of Electrical Engineers of Japan, 4-042 (2011) further discloses a technique for converting an input waveform into a sinusoidal waveform, and increasing efficiency.
Japanese Patent Application Laid-Open No. 2011-193678 and Japanese Patent Application Laid-Open No. 2012-135184 applied by the applicant of the present application are listed as documents that disclose techniques relating to the present application.